It is known that when sitting in a simple straight back chair for a long period of time, one can experience strain on the back and neck muscles. Ergonomists have suggested that minimizing strain requires frequent relaxation of the muscles which can be done by leaning back from time to time.
Many present inventions are aimed at allowing the user to lean back; however, they tend to be complex or difficult to install. Many of these inventions have multiple parts causing them to be costly and time consuming to manufacture. Some chairs that allow the user to lean back have the backrest attached directly to the seat, forcing the seat to tilt back with the backrest. Other chairs have vertical spring systems attaching the backrest to the seat assembly. These are often embedded in the hollow tubing used to construct the chair, complicating the manufacturing process. Many chairs with flexible backrests have bulky spring systems, taking away from the chairs aesthetic value.